The Journal of Oral Laser Applications
J Oral Laser Applications 10 (2010), No. 4     14. June 2011
J Oral Laser Applications 8 (2008), No. 1  (18.03.2008)

Page 25-31

Comparative Study of Dentin Surface Changes Following Nd:YAG and Er:YAG Lasers Irradiation and Implications for Hypersensitivity
Birang, Reza / Yaghini, Jaber / Shirani, Amir Mansour
Purpose: Dentin hypersensivity (DH) is one of the most common complications occurring after periodontal treatment. Various methods such as Nd:YAG and Er:YAG have been used to treat DH. Previous studies support the effectiveness of these lasers, but their effect on the tooth surface largely depends on certain parameters of the tooth surface. This study attempts to evaluate some changes of the dentin surface after Nd:YAG and Er:YAG laser irradiation by using SEM.
Materials and Methods: Fifteen freshly extracted mandibular molars were selected, and 4 specimens with known dimensions (1 x 2 x 2 mm) from the buccal surface and below CEJ of all the teeth were prepared to obtain a total of 60 specimens. These specimens were then divided into 4 groups. Group 1 (control) was not subjected to laser irradiation. Group 2 was subjected to Nd:YAG laser irradiation (0.5 W, 50 mJ, 10 Hz, 60 s). Group 3 was irradiated by Nd:YAG laser (1 W, 100 mJ, 10 Hz, 60 s). Group 4 was irradiated by Er:YAG laser (0.3 W, 100 mJ, 3 Hz, 60 s). After preparation and gold coating of specimens, they were observed under SEM. Finally, the number and diameter of dentinal tubules, craters, and microcracks were determined in different groups. Finally, the data were analyzed using ANOVA.
Results: The number of open tubules showed significant differences between the Nd:YAG (1 W) group and other groups (p < 0.05), but no significant differences were observed between the Nd:YAG (0.5 W), Er:YAG (0.3 W), and control groups. Tubule diameter showed significant differences across all groups (p < 0.001), except between the Nd:YAG (1 W) and Er:YAG groups. Craters and carbonization were only observed in some samples of the Er:YAG group. No microcracks were detected in the study groups.
Conclusion: The results of this study show that Nd:YAG and Er:YAG laser irradiation can cause thermal effects such as decreased dentinal tubule diameter or occlusion. According to this study, the Nd:YAG laser at 1 W power is more effective than the Nd:YAG at 0.5 W or Er:YAG in occluding tubules.

Keywords: dentin hypersensitivity, Nd:YAG laser, Er:YAG laser, dentinal tubule, scanning electron microscope (SEM)